Fuel 'prime' problem-no start?
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Freshman User
Joined: Sep 2007
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Fuel 'prime' problem-no start?
Well guys my first post, and with a problem, of course! '91 F350 dually, 7.3 ('94 reman-no clue on miles). Gradually the truck has been getting harder, and harder ,to start when cold-crank, pump the pedal, and crank. Sometimes, if I don't touch the pedal it will start run for one or two seconds and die. Once warmed up, no problem, but overnight-no go. So, I changed the lift pump on the block(what a @#$*^! job!). Checked the glow plugs, one dead, replaced that. Then, it was even harder to start! Man, I'm going to change the fuel filter, and air filter! Guess what? Hasn't started yet- the batteries are on the charger! The manual I have talks about air in the 'suction lines'-what the He.... are 'suction lines'. Bill
New User
Joined: Jul 2007
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I think you'r getting air into the system @ the return fuel lines on the injectors. You probably bumped them replacing the gp, thats why it got worse. There are o rings under the plastic connections on the injectors that get hard from the heat or the lines themself may be letting air in. they don't have to leak fuel to let air in, as air is a smaller molecule than fuel. You can get a return line kit for around $30.00 to $35.00 that has everthing in it. No clue as to the suction line, unless they mean the line from the tank to the tank controll valve and then to the pump.
Good luck
Good luck
Elder User
Joined: Aug 2007
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the suction line is the fuel line from the tank through the lift pump all teh way to the injector pump , the injector pump can pull up to 30 inches of vacuum and will ingest air anywhere there is the slightest leak
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Freshman User
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Air leak
Thanks guys, that's a start. I could have done something to the injector lines-some of the glow plug wires were hard to get off-wiggling my hands to get to the plugs. Several were so brittle the plastic caps broke.
Post Fiend
Joined: Nov 2003
Posts: 21,285
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From: Nutter Fort, WV
BubbaBud,
Welcome to FTE and the IDI diesel forum.
As others have said, I think your problem is in the return lines.
Replace all the O rings and rubber fuel lines at the same time.
Learned this the hard way many years ago.
Welcome to FTE and the IDI diesel forum.
As others have said, I think your problem is in the return lines.
Replace all the O rings and rubber fuel lines at the same time.
Learned this the hard way many years ago.
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Freshman User
Joined: Sep 2007
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Several years ago, a mechanic told me to cut off pieces of (I think 1/4") fuel line and use them as 'O' rings at the injectors. That appeared to work for some time. I guess the thing that confuses me is why it starts and runs well once warmed up. You'd think an air leak would be there all the time. I'll give the lines/ 'O' rings a try-probably time anyway!
Posting Guru
Joined: Mar 2005
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From: KY
Originally Posted by BubbaBud
Several years ago, a mechanic told me to cut off pieces of (I think 1/4") fuel line and use them as 'O' rings at the injectors. That appeared to work for some time. I guess the thing that confuses me is why it starts and runs well once warmed up. You'd think an air leak would be there all the time. I'll give the lines/ 'O' rings a try-probably time anyway!
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Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
As small as the O rings are, if a piece of 1/4" fuel line was used as an O ring, the plastic caps are probably cracked.
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